Piston expander



March 17, 1936; w. J. SIX

PISTON EXPANDER Original Filed Oct. 10, 1932 INVENTOR. Wm 75/? J 57x.

ATTORNEYS.

Patented Mar. 17, 1936 UNITED STATES- 2,034,004 rrs'ron EXPANDER waiter J. six.

Indianapolis, Ind.

Original application October 10, 1932, Serial No.

637,032. 8, 1934, S rial No.

Divided and this application October 14 Claims. (Cl. 309-12) This invention relates to expanding means for skirts of pistons adapted for use in engines, such as internal combustion engines, compression engines, steam engines and the like, being a division of my copending application Serial No. 637,032, 10, 1932, entitled Piston expander.

It is and a skirt which is partially from the head by a circumferential opening or openings. The lands between the ring grooves on the head are usually made slightly smallerin ameter than the diameter of the skirt which is formed initially to close'zy fit the interior of the cylinder. The skirt particularly when formed of aluminum or similar metal, is usually slotted longitudinallyto permit the skirt to expand and contract so that it will closely follow the cylinder wall. However, due to wear of the cylinder and the piston, this closeness of fit between the skirt andthe cylinder wall is soon destroyed with the attendant results of piston slap undue leakage of the oil past the piston rings, and decreased efllciency of-the engine.

these defects without reboring the cylinders or replacing thepistons, it has been heretofore suggested that spring means of some sort within the skirt be provided to expand The principal object of my invention is to provide an improved and simple expander which exerts an expansive action substantially about the entire skirt while permitting the skirt to contract when necessary in operation, a more perfect fit between the cylinder wall than has been possible heretofore.

The invention resides in a compressible spring expander adapted to be compressed within a worn exert outward pressure against the skirt. More particularly, it relates to expanders of simple form having a plurality of downwardly extending folds which may form in effect a split wall adapted to engage-and bear against the inner surface of the piston skirt over a substantial area to force it radially outward to conformto a worn or out-of-round cylinder. For this purpose, a pair of oppositely disposed expanding wall sections bear against the slotted portion of the skirt and that portion opposite thereto, while another pair of wall sections engage and press outwardly against the opposed boss portions, to expand the circumferential length of the skirt.

The full nature of the invention will be more clearly understood from the accompanying drawing and the following description and claims:

55 Fig. 1 is a central vertical section through a portions or piston with the expander mounted therein. Fig. 2

is a plan view of the under side of the piston showing the expander therein. Fig. 3 is a perspective view of the expander removed from the piston. f

In the drawing there is shown a piston of the usual type having a head Ill, piston ring grooves II, a peripheral slot l2 partially separating. the head from the skirt i3, and inwardly extending projections in the form of piston pin bosses i l 10 through which piston pin l5 extends.

Said skirt is provided with the usual substantialiy longitudinal slot I20. extending from the lower end to the peripheral slot lion one side thereof intermediate the bosses, to ermit of ex- 1g; pansion and contraction to conform to the cylinder in which it operates.

For yieldingly expanding said skirt and imparting thereto a radial outward force under spring tension, there is provided an expander 20 spring as illustrated in Fig. 3. Said spring is substantially cup-like", being adapted to be forced in inverted position upwardly within the piston skirt toward the head so that the downwardly extending expanding portions or wall sections 25 bear against the inner surface or side walls of the split skirt To permit of pressure, it may portion l6 adapted head. Extending downwardly from said bight portion, there are a pair'of wall sections or resilient portionsll curved to conform with the curvature of the piston skirt and adapted to be forced inwairdly against the inherent spring tension therein when mounted within the skirt so as to. normally exert an outward pressure thereupon. Intermediate said portions I1, there are oppositely disposed wall sections l8, which are so arranged as to engage the bosses M to normally exert an outward pressure against said bosses and the corresponding side of the skirt.

Said sections i8 extend downwardly about said bosses to embrace The expander embodies suitable expansion folds or expansible formations 20 responding wall sections l1 and IE to permit them to flex relative to each other under spring tension.

From the wherein a piston having a operate in an enlarged cylinder or an out-ofround cylinder, or wherein said piston has lost its normal inherent expanding force. the installation of said expander therein will cause the foregoing, it will be observedthat 5 split skirt is caused to to lie adjacent the piston 30 of contraction therein and the yielding character of pander.

It will also be noted that by reason of the cupshaped integral formation of the expander, it may be readily inserted in the piston and driven home therein without the While the invention has been herein described as applied to the standard type oi split piston, it is also applicable to other types of piston including the so-calied T-slot type. I

The invention claimed is:

1. In combination with a piston having a slotted skirt, piston pin bosses and a piston pin, a cup-shaped spring expander comprising a continuous wail extending downwardly substantially the exbosses, and expansible formations spaced around and having openings through which the piston pin extends.

and extending into engagement with the skirt through which said piston pin extends.

opposite sides of the split of the skirt, each side of the expander having expansible formations, and also openings adJacent the boss-engaging requirement of unusual es, said wall. having openings the skirt of a piston, said expander being formed having aplurality of inwardly looped expansible formations spaced thereabout.

8; In combination with a piston having a split skirt, piston parallel sides adapted to press against said bosses, the ends of the expander being adapted to engage and press against the piston skirt intermediate said bosses, and each side of the expander having vertically extending expansible formations adJacent the engaging ends of the expande 11. A one-piece piston skirt expander formed of spring metal and forming a continuous inteand having parallel sides adapted to press against said bosses, the ends of the expander being the piston skirt intermediate the bosses and each side of the expander having vertical yielding formations adjacent the pin' cal yielding formation provided for permitting contraction thereof.

WALTER J. SIX. 

